The answer is: Eli's hot chocolate is more chocolatey.
The explanation is shown below:
The problem says that Arjur adds 20 mL of chocolate syrup for every 3 ounces of hot water and Eli adds 45 mL of chocolate syrup for every 3 ounces of hot water.
So, as you can see, the amount of chocolate syrup that Eli adds is greater than the amount of chocolate syrup that Arjur adds (45 mL>20 mL). Therefore, his hot chocolate has more syrup and it is more chocolately.